If you own a Lotus Esprit, then its wise to routinely check the water pump weep hole and see if there are signs of a coolant stain mark.
If there is a stain mark or coolant beads emerging from below the V-pulley, then this indicates the mechanical seal is beginning to leak.
At some point in time this situation is going to present itself and its important to be informed about the various replacement options.
Because of the water pump's restricted location (and being time consuming to replace), Esprit owners need to be mindful of carrying out this job only once.
Re-manufactured water pump for Lotus Esprit S4s
1) Purchase a brand new water pump
Whilst this appears to be an obvious choice it is also the most expensive solution at $400.00 upwards.
However, it is questionable if this option offers value for money when comparing other water pump prices.
Opting to install a new water pump in a Lotus Esprit has a down side as the replacement unit employs an inferior seal that has a limited service life.
So why install a new water pump that has the same inherent component problems?
2) Purchase an overhaul kit
For any Lotus Esprit owner, purchasing an overhaul kit from the UK at GBP60.00 (plus postage etc.) may appear to be a cost effective solution.
However, purchasing the above kit does not necessarily offer value for money as invariably just the mechanical seal and bearing need replacing.
So why purchase an impellor and drive flange when the original components can usually be reused?
Replacing the bearing, seal and impellor does not automatically guarantee a quality result as this simplistic approach ignores any pre-existing corrosion (including porosity) and manufacturing tolerances of the pump components.
From 20 years plus of experience of rebuilding water pumps, the mechanical seal needs to be installed at the correct height to maximise service life.
Every water pump seal has been designed by the manufacturer to be installed at specified height that has a very small tolerance.
If the seal installed height is significantly reduced, too much crush will result and the seal will fail prematurely.
Conversely, if the recommended installed height is exceeded, then there is not enough crush and the seal will leak.
Before any pump can be finally assembled, the surface adjacent to the impellor blades needs to be examined for corrosion (appears as small cavities or holes)
If surface corrosion is present, then this needs to be rectified by machining the pump body in a lathe until a smooth finish is obtained.
Ignoring the corroded surface adjacent to the impellor will cause cavitation and in turn reduce the pump efficiency.
If machining is required to remove corrosion adjacent to the impellor blades, then it is necessary to machine material from the impellor thrust face to compensate for the dimensional changes.
3) Purchase a second hand water pump
Whilst this may seem a good idea, there is not an easy way to check a pump once it has been removed from the vehicle.
Pressure testing the water pump with a custom rig is one way to determine the servieability of the mechanical seal.
Turning the spindle via the drive flange or impellor may provide some indication as to the serviceability of the bearing.
As the bearing spindle is rotated, a certain amount of resistance should be experienced which is the mechanical seal rubbing on the impellor thrust face.
If little or no resistance is felt then the mechanical seal is worn out and the pump is going to leak.
Fitting a second hand pump or an existing pump that has been allowed dry out has the potential to fail prematurely when returned to service.
This is caused by the original seal running directly in contact with the cast-iron impellor thrust face that is guaranteed to be rusty after the coolant has been removed.
From experience the rusty impellor thrust face is highly abrasive and as it rotates, gradually removes material from the seal to a point where it no longer retain the coolant pressure.
At this point coolant will leak out of the weep hole located underneath the pump, indicating it needs to be replaced.
Failing to replace the bearing and seal (prior to installing a second-hand water pump) can be likened to the Challenger Space Shuttle disaster where one of the fuel tanks ruptured due to a faulty seal.
4) Rebuilding the original water pump
Lotus Marques saves customers money by refurbishing the existing components so they can be returned to service.
When rebuilding a customers original pump we install a superior ceramic seal that offers a significantly extended service life.
All components are carefully bead blasted and inspected for serviceability.
If there is any corrosion present in the impellor blades or in the adjacent surface behind the impellor, these components can be machined to recover them.
It is vital the impeller blades and the adjacent swept surface be completely flat so as to prevent cavitation.
Therefore the swept surface must be free of corrosion holes or irregularities caused by the impellor blades removing material from the alloy housing (the result of a worn bearing allowing the impellor blades to make mechanical contact with the swept surface).
The impellor thrust face is machined to accept the ceramic seal and to set the seal height to the manufactures specifications.
All water pumps are dummy assembled to check the seal installed height and then the seal is lapped with metal polish (to guarantee a perfect seal)
Once the pump is fully assembled, its then pressure tested to 50psi ensuring it does not leak once re-installed.
From experience, if the mechanical seal is not installed at the manufacturers recommended height and and pressure testing is not carried out, then it's unreasonable to expect the water pump to offer optimal service life.
Pricing
As a cost entry point, most Lotus Esprit water pumps can be rebuilt for approximately $150.00 plus GST
This includes dismantling, cleaning, bead blasting, dummy assembly, adjusting seal installed height to manufacturers specifications, supply and fit ceramic seal and bearing, final assembly and pressure test.
In the event of receiving a heavily corroded pump, additional rectification costs can arise and will be determined once the pump has been dismantled and inspected.
At this point Lotus Marques will provide a firm quotation for any of the following operations required to recover the pump.
a) Machining corroded impellor blades
b) Machining corroded internal pump body surface adjacent to impellor
c) Welding corroded pump inlet or any other corroded areas
d) Replacement of corroded 5/8" elbow (supply and install brass threaded fitting)
e) Replacement of corroded 5/8" straight stub (supply and install brass threaded fitting)
Summary
As from 8/10/2016 Lotus Marques is no longer able to offer change over water pumps because of the increasing numbers of pumps that have corrosion.
From experience, it is possible to refurbish other water pumps from all models of Lotus Esprit, Excel, Elite, Eclat and Jensen Healey.
PLEASE NOTE CAREFULLY
Lotus Marques does not supply components or rebuild kits so individuals may attempt to rebuild pumps and then have them fail prematurely. Instead we provide a comprehensive rebuild service where the water pump is guaranteed not to leak and will provide an extended service life.
| Qualified engineering personnel |
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| Ceramic seal upgrade as standard |
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Pressure tested to 50psi
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| Same day turn around service |
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Two year parts and labour warranty
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| Remanufactured by Lotus Marques |
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For more information regarding the water pump refurbishment service available from Lotus Marques, see the relevant data sheet here.
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